BEC/Fraud: Generic Scam attempt to Undisclosed Receipients

 1name: "BEC/Fraud: Generic Scam attempt to Undisclosed Receipients"
 2description: |
 3    Detects potential generic scams by analyzing text within the email body and other suspicious signals.
 4type: "rule"
 5severity: "low"
 6source: |
 7  type.inbound
 8
 9  // undisclosed recipients
10  and any([recipients.to, recipients.bcc, recipients.cc],
11          any(., .display_name =~ "Undisclosed recipients")
12  )
13
14  // mismatched sender (from) and Reply-to
15  and any(headers.reply_to,
16          length(headers.reply_to) > 0
17          and all(headers.reply_to,
18                  .email.domain.root_domain != sender.email.domain.root_domain
19          )
20  )
21
22  // generic recipient
23  and any(ml.nlu_classifier(body.current_thread.text).entities,
24          .name == "recipient" and regex.icontains(.text, "(sir|madam)")
25  )
26
27  // request made
28  and any(ml.nlu_classifier(body.current_thread.text).entities,
29          .name == "request")
30
31  // not a bec scam
32  and all(ml.nlu_classifier(body.current_thread.text).intents,
33          .name != "bec"
34  )
35
36  // negate highly trusted sender domains unless they fail DMARC authentication
37  and (
38    (
39      sender.email.domain.root_domain in $high_trust_sender_root_domains
40      and not headers.auth_summary.dmarc.pass
41    )
42    or sender.email.domain.root_domain not in $high_trust_sender_root_domains
43  )
44  and (
45    (
46      profile.by_sender().prevalence in ("new", "outlier")
47      and not profile.by_sender().solicited
48    )
49    or (
50      profile.by_sender().any_messages_malicious_or_spam
51      and not profile.by_sender().any_false_positives
52    )
53  )
54  and not profile.by_sender().any_false_positives  
55
56
57attack_types:
58  - "BEC/Fraud"
59tactics_and_techniques:
60  - "Social engineering"
61detection_methods:
62  - "Content analysis"
63  - "Header analysis"
64  - "Natural Language Understanding"
65  - "Sender analysis"
66id: "5dac401f-d3c1-5092-aba4-58ab597c702b"